On 09/07/16 03:09, Mitchel Humpherys wrote:
> The newly added DMA_ATTR_PRIVILEGED_EXECUTABLE is useful for creating
> mappings that are executable by privileged DMA engines. Implement it in
> dma-iommu.c so that the ARM64 DMA IOMMU mapper can make use of it.
>
> Signed-off-by: Mitchel Humpherys <mitch...@codeaurora.org>
> ---
> arch/arm64/mm/dma-mapping.c | 6 +++---
> drivers/iommu/dma-iommu.c | 15 +++++++++++----
> include/linux/dma-iommu.h | 3 ++-
> 3 files changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index c566ec83719f..44f676268df6 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -543,7 +543,7 @@ static void *__iommu_alloc_attrs(struct device *dev,
> size_t size,
> struct dma_attrs *attrs)
> {
> bool coherent = is_device_dma_coherent(dev);
> - int ioprot = dma_direction_to_prot(DMA_BIDIRECTIONAL, coherent);
> + int ioprot = dma_direction_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
> size_t iosize = size;
> void *addr;
>
> @@ -697,7 +697,7 @@ static dma_addr_t __iommu_map_page(struct device *dev,
> struct page *page,
> struct dma_attrs *attrs)
> {
> bool coherent = is_device_dma_coherent(dev);
> - int prot = dma_direction_to_prot(dir, coherent);
> + int prot = dma_direction_to_prot(dir, coherent, attrs);
> dma_addr_t dev_addr = iommu_dma_map_page(dev, page, offset, size, prot);
>
> if (!iommu_dma_mapping_error(dev, dev_addr) &&
> @@ -755,7 +755,7 @@ static int __iommu_map_sg_attrs(struct device *dev,
> struct scatterlist *sgl,
> __iommu_sync_sg_for_device(dev, sgl, nelems, dir);
>
> return iommu_dma_map_sg(dev, sgl, nelems,
> - dma_direction_to_prot(dir, coherent));
> + dma_direction_to_prot(dir, coherent, attrs));
> }
>
> static void __iommu_unmap_sg_attrs(struct device *dev,
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index ea5a9ebf0f78..ccc6219da228 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -132,23 +132,30 @@ EXPORT_SYMBOL(iommu_dma_init_domain);
> * dma_direction_to_prot - Translate DMA API directions to IOMMU API page
> flags
Privilege really isn't a direction :(
If we're going to cram more into this function it really wants renaming
and redocumenting.
> * @dir: Direction of DMA transfer
> * @coherent: Is the DMA master cache-coherent?
> + * @attrs: DMA attributes for the mapping
> *
> * Return: corresponding IOMMU API page protection flags
> */
> -int dma_direction_to_prot(enum dma_data_direction dir, bool coherent)
> +int dma_direction_to_prot(enum dma_data_direction dir, bool coherent,
> + struct dma_attrs *attrs)
> {
> int prot = coherent ? IOMMU_CACHE : 0;
>
> switch (dir) {
> case DMA_BIDIRECTIONAL:
> - return prot | IOMMU_READ | IOMMU_WRITE;
> + prot |= IOMMU_READ | IOMMU_WRITE;
> case DMA_TO_DEVICE:
> - return prot | IOMMU_READ;
> + prot |= IOMMU_READ;
> case DMA_FROM_DEVICE:
> - return prot | IOMMU_WRITE;
> + prot |= IOMMU_WRITE;
> default:
> return 0;
> }
> + if (dma_get_attr(DMA_ATTR_PRIVILEGED_EXECUTABLE, attrs)) {
> + prot &= ~IOMMU_WRITE;
Hey, we didn't say anything anywhere about anything being privileged
read-only! Frankly, I think this is going to create more problems that
it solves. Implementing IOMMU_PRIV as simply unprivileged no-access
should be sufficient.
Robin.
> + prot |= IOMMU_PRIV;
> + }
> + return prot;
> }
>
> static struct iova *__alloc_iova(struct iova_domain *iovad, size_t size,
> diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h
> index 8443bbb5c071..d5a37e58d29b 100644
> --- a/include/linux/dma-iommu.h
> +++ b/include/linux/dma-iommu.h
> @@ -32,7 +32,8 @@ void iommu_put_dma_cookie(struct iommu_domain *domain);
> int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base, u64
> size);
>
> /* General helpers for DMA-API <-> IOMMU-API interaction */
> -int dma_direction_to_prot(enum dma_data_direction dir, bool coherent);
> +int dma_direction_to_prot(enum dma_data_direction dir, bool coherent,
> + struct dma_attrs *attrs);
>
> /*
> * These implement the bulk of the relevant DMA mapping callbacks, but
> require
>
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